Minutes of the LIS Section meeting held on 25^th August 2008

Present: G. Arduini, S. Aumon, J. Barranco, E. Benedetto, O. Berrig, A. Franchi, S. Gilardoni, S. Maury, E. Métral, D. Quatraro, G. Rumolo

General Information (Gianluigi)

Volunteers are required for receiving the press in the CCC conference room during the event on 10/9

Technical and Doctoral Student requests should be addressed to Oliver by 10/9 (with copy to Gianluigi)

The second synchronization test took place during the week-end 23-24 August with injection of Beam 2 from point 8 to point 7. An important dispersion mismatch has been found and investigations are ongoing in order to understand the origin of that. Injection of Beam 1 from point 2 to point 3 took place as well in order to resolve the issues in the optics errors observed during the previous injection test. The errors have been identified (wrong polarity convention in the database) and corrected. Now the agreement between measurements and model is very good.

HEADTAIL Upgrade - New Features and Options (Diego) - slides

Diego presented the new features and options for the HEADTAIL code. The slides should be added to the SPS Impedance Web page. A manual is being written and a link to the SPS impedance web page should be added as well. Action: Diego, Giovanni.

Diego showed also some recent results on the simulated bunch mode spectrum vs. bunch population for the SPS taking into account the resistive wall impedance of the kickers. The models taking into account the distribution of the impedances in the machine and an effective one representing the distributed impedance with a single impedance source in a position of the machine give very similar results. A negative slope in the dependence of the horizontal mode 0 frequency vs. intensity is observed while the measurements indicate a positive slope. This needs to be understood and the effect of the other elements (e.g. BPMs ) for which simulations exist should be added to see whether this could explain the discrepancy. Action: Benoit, Elias.

Status of the PS Injection Studies (Sandra) - slides

The preliminary results of an experiment conducted seem to indicate that the losses generating radiation in the Goward Road occur at the PS Injection Septum. There are indications that the loss does not occur right at injection but it seems that these are produced during subsequent turns. For that reason a detailed study of the injection mismatch have started (both dispersion and betatronic mismatch). From the first measurements there are indications of a mismatch between the dispersion extrapolated at the injection septum from the measurements in the line and that extrapolated at the septum form the measurements of the dispersion at the first turn in the ring. This could indicate an error in the representation of the stray fields in the last part of the injection line.

It is also clear that there is an important dispersion mismatch at injection that could be at the origin of the losses at the septum in the turns following injection.

Round-table (all)

MTE (Simone)

The issue of the reproducibility of the capture on a cycle-by-cycle basis is not yet resolved. No important sources of noise in the power converters have been found so far.

The performance of the instrumentation is still poor: the orbit measurement is not working at high energy and frequent re-boots of the wire scanner front-ends are required.

FT61 model (Olav)

Olav has completed the MAD-X model of the FT61 line. Some discrepancies have been found between the layout drawings and the survey data. Olav is going to organize a meeting with T. Dobers.

Next meeting

Monday, 8^th September 2008 at 10:00 in room 354-1-001

Agenda

General Information (Gianluigi)

Highlights from HB08 (Elias, Michel Martini)

Round Table (all)

A.O.B.

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